This invention relates generally to a system for detecting defective wheels of a railroad car while the train is moving, and more particularly to such a system for automatically detecting a thin flange condition as well as a loose wheel condition of the railroad car.
A "thin flange" wheel condition referred to herein relates to the thickness of a wheel flange reduced through wear or faulty manufacture from a predetermined flange thickness of 1.0 inch minimum measured from the back face of the rim of the wheel to a typical gauging point on the flange. Such a gauging point is shown in U.S. Pat. No. 3,938,254, for example, as determined with the use of a standard manual gauge (Association of American Railroads steel wheel gauge). And, a "loose wheel" or "slipped wheel" condition described herein refers to slippage of a railroad car wheel relative to its axle. In such condition, railroad car wheels of an opposed pair shift closer together than the prescribed minimum distance of 53 inches prescribed by the AAR. The permissible spacing between back faces of the rims of opposed wheels is 53 to 533/8 inches.
Manual wheel flange gauges of the type described in the aforementioned patent, and manual measurements are customarily taken to gauge the thin flange and loose wheel conditions during an immobile condition of the railroad car in the yard. Such manual gauging and measurement techniques are manifestly laborious and time consuming and not sufficiently accurate because of human error involved.